Class 6 Science Chapter 9 Methods of Separation in Everyday Life – NCERT Solutions, Notes & Worksheet
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Class 6 Science Chapter 9 – Methods of Separation in Everyday Life
NCERT Curiosity 2026-27 | Detailed Notes, NCERT Questions & Answers, Important Questions, MCQs & Worksheet
In everyday life, we often find two or more substances mixed together. We separate them when we need to remove an unwanted component or when we want to collect useful components separately. The method of separation is selected according to the properties in which the components differ.
๐ 1. Why Do We Separate Substances?
A mixture contains two or more substances together. In many situations, the components of a mixture have to be separated. Separation may be needed to remove an unwanted or harmful substance, or to obtain useful components separately.
- Removing unwanted material, such as stones from rice or pulses.
- Obtaining useful products separately, such as butter from curd.
- Cleaning materials before use, such as removing unwanted particles from water.
๐น 2. Handpicking
Handpicking is a simple method in which unwanted components are picked out by hand. It is useful when the unwanted material is easily visible, sufficiently large and present in a comparatively small amount.
Example: Removing stones from rice or pulses.
Principle: Visible difference in appearance, size or shape.
๐น 3. Threshing
Threshing is used to separate grains from the stalks of harvested crops. The stalks are beaten or subjected to mechanical action so that the grains are released.
๐น 4. Winnowing
Winnowing uses moving air to separate lighter material from heavier material. When a mixture of grains and lighter husk is allowed to fall in moving air, the lighter husk is carried farther away while the heavier grains fall nearer.
Example: Separating husk from grains.
Principle: Difference in weight/lightness.
๐น 5. Sieving
Sieving is used to separate solid particles of different sizes. A sieve has holes of a particular size. Smaller particles pass through the holes, while larger particles remain on the sieve.
Examples: Separating larger unwanted particles from flour; separating differently sized solid particles.
Principle: Difference in particle size.
๐น 6. Sedimentation
When an insoluble solid is mixed with a liquid and the mixture is left undisturbed, the heavier solid particles gradually settle at the bottom. This process is called sedimentation.
Example: Muddy water left undisturbed for some time.
The solid that settles at the bottom is called the sediment.
๐น 7. Decantation
After sedimentation, the clearer liquid above the settled solid can be carefully poured into another container without disturbing the sediment. This process is called decantation.
• Sedimentation = solid particles settle down.
• Decantation = clearer liquid is carefully poured off.
๐น 8. Filtration
Filtration separates an insoluble solid from a liquid by passing the mixture through a filter. The liquid passes through the pores of the filter, while suitable solid particles are retained.
Examples: Separating tea leaves from tea; separating sand from water.
Residue: The solid retained on the filter.
Filtrate: The liquid that passes through the filter.
๐น 9. Evaporation
Evaporation is the process in which a liquid changes into vapour. It can be used to obtain a dissolved solid from a solution when the liquid is allowed to evaporate.
Example: Obtaining salt from seawater.
๐น 10. Churning
Churning is used to separate components such as butter and the liquid portion of curd. The mixture is churned or stirred repeatedly, allowing the butter to separate.
Example: Separating butter from curd.
๐น 11. Magnetic Separation
Some materials are attracted by a magnet while others are not. A magnet can therefore be used to separate a magnetic material from a non-magnetic material.
Example: Separating iron powder from sawdust.
Principle: Difference in magnetic property.
๐ 12. Separation Methods at a Glance
| Method | Used to separate | Main principle |
|---|---|---|
| Handpicking | Stones from rice | Visible difference |
| Threshing | Grain from stalks | Mechanical action |
| Winnowing | Husk from grain | Difference in weight |
| Sieving | Different-sized solids | Particle size |
| Sedimentation | Heavy solid from liquid | Settling |
| Decantation | Clear liquid from settled solid | Settling |
| Filtration | Insoluble solid from liquid | Filter pores |
| Evaporation | Dissolved solid from solution | Evaporation |
| Churning | Butter from curd | Physical properties |
| Magnetic separation | Iron from non-magnetic material | Magnetism |
๐ง 13. How to Choose the Correct Separation Method?
- Visible unwanted material → Handpicking
- Grains and stalks → Threshing
- Light and heavy materials → Winnowing
- Different particle sizes → Sieving
- Heavy insoluble solid settles → Sedimentation + Decantation
- Insoluble solid in liquid → Filtration
- Dissolved solid in liquid → Evaporation
- Butter from curd → Churning
- Magnetic material → Magnetic Separation
๐ NCERT Textbook Questions & Answers
Q1. What purpose does handpicking serve in the process of separation?
Answer: Handpicking is used for sorting. It helps us remove an easily visible unwanted component from a mixture by picking it out by hand.
Q2. Which substance is commonly separated using the churning method?
Answer: Butter or cream is separated from curd or milk by churning.
Q3. Which factor is usually essential for filtration?
Answer: The pore size of the filter is important. The filter should allow the liquid to pass through while retaining the solid particles.
Q4. State with reasons whether the statements about separation methods are true or false.
Answer:
- Salt can be obtained from a salt solution by keeping it under the Sun — True.
- Handpicking is useful when an unwanted component is present in a small quantity and can be easily seen — True.
- Puffed rice and rice grains can be separated by threshing — False. Threshing separates grains from stalks.
- Sieving can separate mustard oil and lemon water — False. Sieving is mainly used for solid particles of different sizes.
- Filtration can separate dissolved salt from water — False. Dissolved salt passes through the filter.
Q5. Match the mixtures with the appropriate separation method.
| Mixture | Method |
|---|---|
| Gram flour + black gram | Handpicking |
| Chalk powder + water | Filtration |
| Corn + potatoes | Handpicking / sorting |
| Iron powder + sawdust | Magnetic separation |
| Oil + water | Decantation |
Q6. When would you use decantation instead of filtration?
Answer: Decantation is useful when the heavier insoluble solid has settled at the bottom and the clearer liquid above it can be carefully poured out.
Q7. How are nasal hairs related to a separation process?
Answer: Nasal hairs trap dust and other particles from the air we breathe. Their function is similar to filtration because they prevent some unwanted particles from entering further into the respiratory passage.
Q8. What is the role of a mask?
Answer: Masks are generally made from layers of fabric or non-woven material. They act as a filtering barrier by helping block many particles and droplets while allowing air to pass.
Q9. How can you separate potatoes, salt and sawdust from their mixture?
Answer:
- Handpick the potatoes because they are large and easily distinguishable.
- Add water to the remaining mixture. Salt dissolves in water while sawdust does not.
- Filter the mixture to separate sawdust from the salt solution.
- Evaporate the water from the filtrate to obtain salt.
Q10. What do we learn from the story “Intelligent Leela”?
Answer: The story shows that a mixture may need more than one separation method. The appropriate sequence depends on the properties of the unwanted materials. For muddy water, settling followed by decantation and filtration can remove suspended impurities; further treatment such as boiling may be needed when water is intended for drinking.
⭐ Important Extra Questions & Answers
1. What is a mixture?
Answer: A mixture is formed when two or more substances are present together without forming a new substance.
2. Why do we separate mixtures?
Answer: We separate mixtures to remove unwanted components or to obtain useful components separately.
3. Why is handpicking not suitable for every mixture?
Answer: It is slow and is useful mainly when the unwanted material is clearly visible, sufficiently large and present in a comparatively small quantity.
4. What is the difference between threshing and winnowing?
Answer: Threshing separates grains from stalks by mechanical action, whereas winnowing separates lighter husk from heavier grains using moving air.
5. What is the difference between sedimentation and decantation?
Answer: Sedimentation is the settling of heavier insoluble particles at the bottom. Decantation is carefully pouring out the clearer liquid above the settled particles.
6. What are residue and filtrate?
Answer: Residue is the solid retained on the filter. Filtrate is the liquid that passes through the filter.
7. Why can filtration not separate dissolved salt from water?
Answer: Salt is dissolved in water, so its particles pass through the filter along with the water.
8. How can salt be obtained from seawater?
Answer: Seawater can be allowed to evaporate. Water changes into vapour and salt remains behind.
9. Which method would you use for iron powder and sawdust? Why?
Answer: Magnetic separation, because iron is attracted by a magnet while sawdust is not.
10. Why is sieving based on particle size?
Answer: The holes of a sieve allow smaller particles to pass through while larger particles remain on the sieve.
11. Give two examples of separation methods used in the kitchen.
Answer: Filtration while preparing tea and churning while separating butter from curd.
12. A mixture contains wheat, husk and a few stones. Suggest a suitable sequence of methods.
Answer: First use winnowing to remove the lighter husk from the heavier wheat. Then use handpicking to remove the stones.
๐ Worksheet
A. Choose the correct answer.
1. Which method is used to remove stones from rice?
A) Filtration B) Handpicking C) Evaporation D) Churning
2. Which method separates grains from stalks?
A) Threshing B) Winnowing C) Sieving D) Filtration
3. Winnowing mainly depends on difference in:
A) Colour B) Weight C) Temperature D) Solubility
4. Sieving is mainly based on difference in:
A) Particle size B) Magnetic property C) Colour D) Taste
5. Which method is suitable for obtaining salt from seawater?
A) Handpicking B) Filtration C) Evaporation D) Winnowing
6. Which method separates iron powder from sawdust?
A) Decantation B) Magnetic separation C) Sieving D) Churning
7. Butter can be separated from curd by:
A) Churning B) Filtration C) Winnowing D) Sedimentation
8. The liquid that passes through a filter is called:
A) Residue B) Filtrate C) Sediment D) Solute
B. Fill in the blanks.
9. The process in which heavier insoluble particles settle at the bottom is called __________.
10. Carefully pouring the clearer liquid after sedimentation is called __________.
11. __________ is used to separate grains from stalks.
12. __________ can be used to obtain salt from seawater.
13. A __________ can be used to separate iron from sawdust.
C. True or False.
14. Filtration can separate dissolved salt from water.
15. Winnowing can separate husk from grain.
16. Sieving separates particles according to their size.
17. Churning can separate butter from curd.
18. Sedimentation means carefully pouring the clear liquid into another vessel.
D. Answer in 2–3 sentences.
19. What is handpicking? Give one example.
20. Explain the difference between sedimentation and decantation.
21. Why is filtration useful for separating sand from water?
22. Why is evaporation suitable for obtaining salt from salt water?
23. What property is used in magnetic separation?
E. Competency-Based Question
✅ Answer Key
MCQs: 1-B, 2-A, 3-B, 4-A, 5-C, 6-B, 7-A, 8-B
Fill in the blanks: 9. Sedimentation 10. Decantation 11. Threshing 12. Evaporation 13. Magnet
True/False: 14. False 15. True 16. True 17. True 18. False
Handpicking → visible unwanted material
Threshing → grain from stalks
Winnowing → lighter husk from grain
Sieving → separation by size
Sedimentation → heavy particles settle
Decantation → clear liquid poured off
Filtration → insoluble solid from liquid
Evaporation → dissolved solid remains
Churning → butter from curd
Magnetic separation → magnetic material
Pathshala Notes • Class 6 Science • NCERT Curiosity 2026–27
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